Heretofore, in controlling a residential environment of the user, an environment control system has been controlled by detecting environmental physical quantities such as a temperature (hereinafter, called as “room temperature”) of the residential environment, a humidity (hereinafter, called as “humidity”) of the residential environment, a temperature (hereinafter, called as “external temperature”) outside the residential environment, and the amount of insolation. Other than the aforementioned control based on the environmental physical quantities, there is proposed an approach of acquiring and analyzing biological information on the user, estimating the status of the user such as a stressful condition, a relaxed condition, an excited condition or the like, and controlling an environment control system based on the estimation result.
For instance, patent document 1 proposes a technique of estimating a psychological status of the user, primarily hot/cold sensations (thermal sensations) by the user's pulse wave amplitude. FIG. 16 is a diagram corresponding to FIG. 5 recited in patent document 1. In patent document 1, correlations between absolute value of pulse wave amplitude (Vp-p in FIG. 16), and thermal sensations (cold/cool/moderately cool/not cold or hot/moderately warm/warm/hot) are expressed by a characteristic curve L. If the absolute value of the user's pulse wave amplitude acquired at a certain point of time is Vpa, the user's thermal sensation is estimated to be “warm”. If the absolute value is Vpb, the user's thermal sensation is estimated to be “cool”. An air-conditioning system is controlled based on the estimation result.
Also, for instance, patent document 2 proposes additionally mounting a temperature sensor and a humidity sensor in a bed. The thermal sensation of the user in bed is estimated by measuring a temperature of a back portion of the user who is about to sleep. The temperature and the humidity of the bedroom are controlled based on an average value of thermal sensations of plural users.
In patent document 1, the absolute value of the user's pulse wave amplitude, and the user's thermal sensation are correlated, and the user's pulse wave amplitude is acquired to estimate the user's thermal sensation based on the acquired absolute value of the user's pulse wave amplitude. Since the pulse wave amplitude differs among individuals, it is not always the case that every user whose absolute value of the pulse wave amplitude is substantially identical has the same thermal sensation. For instance, even if the user A and the user B have an identical absolute value Vpc of the pulse wave amplitude, the user A may have a thermal sensation corresponding to “moderately cool”, and the user B may have a thermal sensation corresponding to “moderately warm”. In other words, since patent document 1 does not consider individual differences in the absolute value of the pulse wave amplitude, the air-conditioning system may overcool the room despite that the user A feels “moderately cool”, thereby making the user A feel uncomfortable. Also, the technology of patent document 1 is made based on the premise that a single user resides in the residential environment, and patent document 1 does not recite a measure to be taken in a case that plural users stay or reside in a common space.
In patent document 2, the temperature of the user's back portion, and the user's thermal sensation are correlated. The temperature of the user's back portion is detected by the temperature sensor mounted in the bed, and the user's thermal sensation (−3: cold, −2: cool −1: moderately cool, 0: not cold or hot, 1: moderately warm, 2: warm, 3: hot) is estimated based on the detected temperature. The correlation between the temperature of the user's back portion and the user's thermal sensation may differ among individuals. For instance, even if the detected temperatures of the back portions of the user A and the user B are substantially identical to each other, the thermal sensation of the user A may correspond to “moderately cool (−1)”, and the thermal sensation of the user B may correspond to “not cold or hot (0)”. In other words, since patent document 2 does not consider individual differences in the correlation between the temperature of the user's back portion and the user's thermal sensation, the air-conditioning system may suspend the cooling operation despite that the user B does not feel hot or cold, thereby making the user B feel uncomfortable. Also, in patent document 2, in the case where plural users stay in a common space, an air-conditioning system is controlled based on the premise that the users stay or reside in the common space (bedroom), using an average thermal sensation obtained by averaging the thermal sensations of the users estimated based on the temperatures of the back portions of the users. However, since the thermal sensations of the users are estimated, without considering individual differences in the correlation between the temperature of the user's back portion and the user's thermal sensation, even with use of the average thermal sensation, the air-conditioning system may fail to perform proper air-conditioning control, considering thermal sensations of the users.    Patent document 1: Japanese Patent No. 2,833,082 (pp. 5-6, FIG. 5)    Patent document 2: Japanese Unexamined Patent Publication No. Hei 6-147593 (pp. 2-3, FIG. 2)